The present invention relates to a slow releasing device for slowly releasing gaseous chlorine dioxide and a method for making the slow releasing device and, more particularly, to a method and a product of carrying gaseous chlorine dioxide in carriers to provide slow, long-term, effective release of chloride dioxide.
Chlorine dioxide is a strong oxidant having excellent effect in disinfection and sterilization and has been known as highly-effective disinfectants, sterilizers, and water-cleaning agents around the globe. The World Health Organization has classified chlorine dioxide as an A1 class (highly safe) disinfectant.
Since gaseous chlorine dioxide is unstable and apt to decompose, the storage, transportation, and use are limited during preparation of liquid chlorine dioxide. Conventionally, there are two main methods of producing solid chlorine dioxide (or dubbed as “stable chlorine dioxide”). One of the methods includes processing gaseous chlorine dioxide into stable solution of chlorite ion (such as by mixing chlorite ion into an alkaline buffer solution). Next, a solidifying agent and a stabilizer are used to absorb the stable solution of chlorite ion and then mixed with a solid acid. The resultant mixture is packaged. In the other method, sodium chlorite and sodium chlorate are used as the matrix, gel is used as auxiliary material, and an acidic substance is used as an activator. These materials are mixed and packaged.
In the above-mentioned methods, the products are solid type and in the form of powders, granules, or ingots, providing slowly-releasing solid products for slowly absorbing moisture. In addition, the solid products can be thrown into water to obtain water solution of gaseous chlorine dioxide after dissolution of the chemical agents. Examples of the methods have been disclosed in Taiwan Patent Application Nos. 087107160, 096102799, 096105956, and 096116154 and U.S. Pat. No. 4,689,169.
However, the by-products and residual organic and inorganic substances in the above-mentioned methods cause reaction of the gaseous chlorine dioxide and oxidizable substances in the water to form ions of chlorite, chlorate, and chloride salts. The desired gaseous chlorine dioxide could not be obtained.
In addition to the stable chlorine dioxide products, water solutions of chlorine dioxide are available on the market, examples of which have been disclosed in U.S. Pat. Nos. 5,296,108 and 5,993,864. However, these products still have many disadvantages. Firstly, conventional manufacturers dissolve chlorine dioxide in water. Thus, the chlorine dioxide is transported or stored in the form of water solution no matter electrolysis or chemical methods are used. However, the gaseous chlorine dioxide is instable and decays in the water into ions of chlorite, chlorate, and chloride salts. Secondly, in a case that the electrolysis equipment is in the same location of user to allow on-site preparation of water solution of chlorine dioxide, a professional worker is required to operate the electrolysis equipment, which is inconvenient to ordinary users. Thirdly, in a case that the chemical methods are used on the site in which various chemical agents are mixed and thrown into the water to produce water solution of chlorine dioxide after chemical reaction in the water, care attention is required to avoid strong reaction must be avoid, and residual chemical substances and by-products are inevitable.